Free spinning laminated nuts utilizing laminations of hex shaped hardened coned-disc springs, formed as a helex or tapped to match the bolt threads are known in the prior art. Such nuts (sold by Peterson-American Corporation under the trademark "Elephant" nuts) have stacked aligned multiple threaded discs retained by a steel outer hex shaped cage. Wrenching dimensions may conform to standard SAE-IFI sizes.
These nuts are free running until seated. Locking load is applied by additional rotation after seating, which compresses and partially flattens the conical spring discs with resulting mechanical interference on the thread flanks due to the change in hole size as the conical disc flattens. This results in thread interference that resists unloading that might otherwise occur as a result of vibration. Thus, the independently loaded conical spring threaded segments when flattened create a thread interference that tends to lock the nut against rotation, or loosening, when subjected to vibration.
As compared to other free spinning locknuts, these nuts effect a dimensional change under loading. They have a conical spring action that enables them to be counter rotated over half a turn or so without loss of total load or loss of interference.
However, the prior art laminated nut, described above, requires for positive locking a secondary operation of adjustment to align holes for cotter key insertion, wiring, or requires mechanical nut deformation into a slot or recess. Further, in the prior art, the loading on the threads of the nut segments in non-uniform, to the extent such that the stress is concentrated in the first thread adjacent the bearing surface. At that point the stress may be as much as 200% or more higher than the average stress in the remaining threads.